Two types of systems for determining the imbalance of a wheel on which a tire is fitted, and for thus balancing it by applying an appropriate weight in preset positions on said wheel, are currently known. The first type is known as static and allows determining the static imbalance of the wheel and the tire. In balancing systems of the static type, the wheel and the tire are not rotated but rather the wheel is centered and supported elastically in a horizontal position. A leveling device, for example provided with a spirit level or the like, the indicator of which moves away from a central reference point depending on the inclination of the wheel and therefore on the static imbalance, is applied to the wheel. The operator then proceeds by fixing adapted counterweights in strategic points of the wheel to return the indicator of the leveling device to the central reference point. This system, however, does not allow compensating for dynamic imbalances caused by the torque effects that act on the wheel.
The second type of system for determining the imbalance of a wheel is known as dynamic, since it allows determining the dynamic imbalance of a wheel, and therefore makes it possible to achieve a more accurate balancing thereof.
In systems of the dynamic type, the wheel to be balanced is mounted on a shaft which is rotated at a preset speed. When said speed is reached, the forces generated by the shaft due to the imbalance of the wheel are measured. Starting from these measurements, which are synchronized with angular rotation signal of the wheel, indications are obtained which relate to the degree of imbalance of the wheel, and therefore the positions and the weights of the counterweights to be applied in order to correct the imbalance are obtained.
Other than with systems of the static type, which can correct only imbalances on a single plane, with systems of the dynamic type it is possible to measure centrifugal forces and therefore also correct dynamic imbalance, i.e., torque imbalance.
Wheel balancing systems of the static and dynamic types are not free from drawbacks, which include the fact that they generally have very bulky and heavy structures, since they are dimensioned so as to be able to support the weight of the wheels, which, in the case of truck wheels, can be quite considerable, and are therefore scarcely maneuverable.
Another drawback of these systems of the known type resides in the fact that they are difficult to move, due to their considerable dimensions and weights; these systems are in fact intended to be used exclusively within garages and workshops.
A further drawback of these systems of the known type resides in the fact that due to their difficult transportability they cannot be used in rescue situations. Currently, particularly in the field of trucks, there are tire changing services that allow the replacement of damaged tires directly in the vicinity of the truck that requires it. On board these rescue vehicles there is a tire removal device that allows removal of the damaged tire and replacement of the same with a working one. However, once tire replacement has been performed, the driver, at a later time, must take care to perform the balancing of the new wheel, in order to benefit from the advantages of durability and comfort provided by a well-balanced wheel, and this causes a further expenditure of time and money.